The present invention relates to rotary fluid pressure devices, and more particularly, to such devices which have two torque-transmitting output shafts, the rotations of which must be synchronized, i.e., must be maintained in a predetermined relationship to each other. In the subject embodiment, and by way of example only, the two output shafts rotate at exactly the same speed.
Although the “dual shaft” motor of the present invention could utilize various types of fluid displacement mechanisms to convert fluid pressure into torque output, the present invention is especially suited for use in a gerotor motor, and therefore, the present invention will be described in connection with a gerotor motor embodiment. Those skilled in the art will understand that as used hereinafter, the term “gerotor” means and includes both a conventional gerotor gear set and a roller gerotor, in which the teeth of the internally-toothed member comprise rollers.
Also, although the present invention may utilize various types of valving, to communicate fluid to and from the fluid displacement mechanism, it is especially advantageous for the present invention to utilize low speed, commutating valving, i.e., valving which rotates at the (low) speed of rotation of the gerotor star, as opposed to the (high) speed of orbital movement of the star. Furthermore, although the present invention may utilize various types of low speed, commutating valving, the present invention is especially adapted for use with valving of the “spool valve” type, as is now quite well known in the gerotor motor art, and the invention will be described in connection therewith.
There are many situations, or vehicle or equipment applications for gerotor motors, in which it would be desirable to provide a “special”, or non-standard gerotor motor to meet certain, unique needs. An example of such a special need, and such a non-standard gerotor motor, is a dual shaft gerotor motor for use in raising and lowering a trailer “stand”, either before or after the trailer is connected to, or detached from, the tractor.
Unfortunately, the engineering effort and development cost to develop such a specialized, dual shaft gerotor motor, for such a relatively low volume application as trailer stands, would typically exceed what is economically justifiable. As a result, gerotor motors have typically not been utilized in this, and a number of other, similar types of applications, for which gerotor motors are especially well-suited, but are simply not commercially available in the particular configuration required.